Slam Toolbox — map file not found

[Pito Salas]

I think we have some slam toolbox and nav2 experts on the list… maybe you can give me some advice?

When I run this:

[vmubuntu:~/ros2_ws] ros2 launch slam_toolbox online_async_launch.py slam_params_file:=src/control/config/mapper_params_online_async.yaml
[INFO] [launch]: All log files can be found below /home/pitosalas/.ros/log/2025-10-16-17-16-29-875893-vmubuntu-7362
[INFO] [launch]: Default logging verbosity is set to INFO

I get this error:

[INFO] [async_slam_toolbox_node-1]: process started with pid [7378]
[async_slam_toolbox_node-1] [INFO] [1760649390.223191787] [slam_toolbox]: Node using stack size 40000000
[async_slam_toolbox_node-1] [INFO] [1760649390.393944219] [slam_toolbox]: Configuring
[async_slam_toolbox_node-1] [INFO] [1760649390.738006125] [slam_toolbox]: Using solver plugin solver_plugins::CeresSolver
[async_slam_toolbox_node-1] [INFO] [1760649390.739338106] [slam_toolbox]: CeresSolver: Using SCHUR_JACOBI preconditioner.
[INFO] [launch.user]: [LifecycleLaunch] Slamtoolbox node is activating.
[async_slam_toolbox_node-1] [ERROR] [1760649390.763262332] [slam_toolbox]: LocalizationSlamToolbox: Incorrect number of arguments for map starting pose. Must be in format: [x, y, theta]. Starting at the origin
[async_slam_toolbox_node-1] [ERROR] [1760649390.763473044] [slam_toolbox]: serialization::Read: Failed to open requested file: basement.
[async_slam_toolbox_node-1] [ERROR] [1760649390.763493669] [slam_toolbox]: DeserializePoseGraph: Failed to read file: basement.
[async_slam_toolbox_node-1] [INFO] [1760649390.767596862] [slam_toolbox]: Activating
[async_slam_toolbox_node-1] [INFO] [1760649391.355272523] [slam_toolbox]: Message Filter dropping message: frame 'laser' at time 1760649391.273 for reason 'discarding message because the queue is full'

Here is the referenced yaml:

slam_toolbox:
ros__parameters:

# Plugin params
solver_plugin: solver_plugins::CeresSolver
ceres_linear_solver: SPARSE_NORMAL_CHOLESKY
ceres_preconditioner: SCHUR_JACOBI
ceres_trust_strategy: LEVENBERG_MARQUARDT
ceres_dogleg_type: TRADITIONAL_DOGLEG
ceres_loss_function: None

# ROS Parameters
odom_frame: odom
map_frame: map
base_frame: base_footprint
scan_topic: /scan
use_map_saver: true
mode: mapping #localization

# if you'd like to immediately start continuing a map at a given pose
# or at the dock, but they are mutually exclusive, if pose is given
# will use pose
map_file_name: basement
# map_start_pose: [0.0, 0.0, 0.0]
# map_start_at_dock: true

debug_logging: false
throttle_scans: 1
transform_publish_period: 0.02 #if 0 never publishes odometry
map_update_interval: 5.0
resolution: 0.05
max_laser_range: 12.0 # For our LD19
minimum_time_interval: 0.5
transform_timeout: 0.2
tf_buffer_duration: 30.0
stack_size_to_use: 40000000 #// program needs a larger stack size to serialize large maps
enable_interactive_mode: true

# General Parameters
use_scan_matching: true
use_scan_barycenter: true
minimum_travel_distance: 0.5
minimum_travel_heading: 0.5
scan_buffer_size: 10
scan_buffer_maximum_scan_distance: 10.0
link_match_minimum_response_fine: 0.1
link_scan_maximum_distance: 1.5
loop_search_maximum_distance: 3.0
do_loop_closing: true
loop_match_minimum_chain_size: 10
loop_match_maximum_variance_coarse: 3.0
loop_match_minimum_response_coarse: 0.35
loop_match_minimum_response_fine: 0.45

# Correlation Parameters - Correlation Parameters
correlation_search_space_dimension: 0.5
correlation_search_space_resolution: 0.01
correlation_search_space_smear_deviation: 0.1

# Correlation Parameters - Loop Closure Parameters
loop_search_space_dimension: 8.0
loop_search_space_resolution: 0.05
loop_search_space_smear_deviation: 0.03

# Scan Matcher Parameters
distance_variance_penalty: 0.5
angle_variance_penalty: 1.0

fine_search_angle_offset: 0.00349
coarse_search_angle_offset: 0.349
coarse_angle_resolution: 0.0349
minimum_angle_penalty: 0.9
minimum_distance_penalty: 0.5
use_response_expansion: true
min_pass_through: 2
occupancy_threshold: 0.1

* I have verified that the yaml file is being read by changing the file path in the launch and seen that it was complaining about not having the file
* I am getting an error message about incorrect number of arguments in starting pose, but it looks correct to me
* I am expecting slam_toolbox to try and create the map instead it says it can't read or open it.
* It does create old-school maps in my ros2_ws/ directory
* I've tried many variations on the path specification and none seem to work. I look for a map in ~/ros2_ws/ and in ~/.ros and in ~/ and never see it

Any recommendations to trouble shoot or fix this little problem?

Best,

Pito Salas
Boston Robot Hackers &&
Computer Science Faculty, Brandeis University

[David Murphy]

Just scanning that file shows the complaint is about starting pose, but that is commented out in the yaml file. Is it provided in some other way?

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[Pito Salas]

I don’t know of any other place where it is provided but I think it must be. Or it’s a side effect of some other setting. I will report back as I do more experiments and more “googling”!

Pito

> To view this discussion visit https://groups.google.com/d/msgid/hbrobotics/CAHtzJazgO2XsYkpaJMDhnT8HiZzPiH2W3-LATwBMkXysbv2zag%40mail.gmail.com.

Best,

Pito

Boston Robot Hackers &&
Comp. Sci Faculty, Brandeis University (Emeritus)

[Michael Wimble]

It’s mostly complaining about your map yaml file. I’m not at a computer right now but you can look at my GitHub for wimblerobotics/sigyn/base/maps and look how how you specify the map file path

> On Oct 17, 2025, at 11:33 AM, Pito Salas <pito...@gmail.com> wrote:
>
> I don’t know of any other place where it is provided but I think it must be. Or it’s a side effect of some other setting. I will report back as I do more experiments and more “googling”!

> To view this discussion visit https://groups.google.com/d/msgid/hbrobotics/AE992615-29F6-44FC-921A-5EC6F730CB6E%40gmail.com.

[Michael Wimble]

I may have misspoke. Is you code in a github where I can look at it?

[David Murphy]

So what happens if you uncomment that line in the yams file?

map_start_pose: [0.0, 0.0, 0.0]

To view this discussion visit https://groups.google.com/d/msgid/hbrobotics/AE992615-29F6-44FC-921A-5EC6F730CB6E%40gmail.com.